Nobrega F G, Tzagoloff A
J Biol Chem. 1980 Oct 25;255(20):9821-7.
The cytoplasmic petite (rho-) mutant DS400/A12 has been obtained from the wild type strain of Saccharomyces cerevisiae D273-10B/A21. The DS400/A12 clone has a mitochondrial genome with a 7.6-kilobase pair, tandemly repeated segment of DNA. Genetic tests indicate that DS400/A12 contains all the cob1 and cob2 markers of the cytochrome b gene. The gene has been further dissected by mutagenesis of DS400/A12 and selection of secondary rho- clones with simpler genotypes. Restriction analysis of the mtDNAs of the rho- clones was used to construct the complete restriction map of the cytochrome b region and to map the mutations within narrowly defined physical limits. The cytochrome b mutants scatter over a maximal distance of 3.3 kilobase pairs. All the mutations assigned previously to the cob2 locus are found between 71.6 and 73.2 units. The cob1 mutations are located between 74.6 and 76.3 units. The estimated distance between the two loci is at least 1 kilobase pair.
细胞质小菌落（rho-）突变体DS400/A12是从酿酒酵母D273-10B/A21的野生型菌株中获得的。DS400/A12克隆具有一个线粒体基因组，其中包含一段7.6千碱基对的串联重复DNA片段。遗传学测试表明，DS400/A12含有细胞色素b基因的所有cob1和cob2标记。通过对DS400/A12进行诱变并选择基因型更简单的次级rho-克隆，对该基因进行了进一步剖析。对rho-克隆的线粒体DNA进行限制性分析，以构建细胞色素b区域的完整限制性图谱，并在狭窄定义的物理范围内定位突变。细胞色素b突变体分布在最大3.3千碱基对的距离上。先前分配到cob2位点的所有突变都位于71.6至73.2单位之间。cob1突变位于74.6至76.3单位之间。两个位点之间的估计距离至少为1千碱基对。
